A front seat automobile headrest includes an energy dissipating function for an object colliding with the back of the front seat of the vehicle when the vehicle undergoes a deceleration caused by a crash or other impact. As a result of the deceleration, the object, typically a rear passenger, having forward momentum continues forward and collides with the back of the front seat. Generally, a seat belt is worn and the body of the passenger is restrained such that the rear passenger's head collides with the back of the headrest.
In the prior art, the energy dissipating function is typically formed by the headrest including a foam core component having a soft material covering. The combination of the foam core and soft covering provides a headrest which compresses during impact, thereby dissipating the resultant energy present as the forward momentum carries the rear passenger into the back of the headrest.
Regulatory standards govern the energy dissipating function of the headrest. Typically, prior art headrest designs have a surface hardness of about 50 Shore A. UN-ECE Regulation 17, titled “Uniform Provisions Concerning the Approval of Vehicles With Regard to the Seats, their Anchorages and Head Restraints,” includes provisions for seats and more specifically headrests. The test for energy dissipation on the rear of a headrest including a pendulum whose pivot is supported by ball-bearings, having a mass at its centre of percussion of 6.8 kg impacting the rear of the headrest at an angle of 45 degrees from the vertical at a speed of 24.1 km/h. The deceleration of the pendulum must not exceed 80 g continuously for more than 3 ms.
Variations in the design of prior art headrests are restricted by the selection of alternative foams and material coverings. There is also an added difficulty in predicting dynamic behavior and performance during the impact of a crash as those skilled in the art will appreciate when working with foam materials. In the absence of easily modeled and simulated dynamic behavior, design has a greater reliance on iterative testing and therefore resulting in a compliant design over longer development times.
The multi-step process of forming material covered foam headrests includes producing the molded and contoured foam core, treating the foam as required and subsequently covering it with the soft material. This process is time consuming, expensive and results in significant wasted materials.
There is a need in the art for an automobile headrest which can be produced more cost effectively and eliminates the need to rely on a foam and soft material to provide the energy dissipating function. There is a further need for a single component headrest which allows for better dynamic behavior modeling such that the difficulties associated with crash simulations and predicting dynamic behavior and performance during a crash can be mitigated such that overall design of the headrest becomes easier.